Oc-cā'sion-al, a.
[It. occasionale, Sp. ocasional, Fr. occasionnel.]
Sense 1. Pertaining to or occurring at times, but not regular or systematic; made or happening as opportunity requires or admits; called out by some occasion; furnishing an occasion; casual; incidental; as, occasional remarks.
Sense 2. Produced by accident; as, the occasional origin of a thing.
Sense 3. Produced or made on some special event; as, an occasional discourse.
Occasional cause (Metaph.), some circumstance preceding an effect which, without being the real cause, becomes the occasion of the action of the efficient cause; thus, the act of touching gunpowder with fire is the occasional, but not the efficient, cause of an explosion.